Investigation of Small Separation of Evolved Stars in Cluster NGC 6811

Abstract

Many solar-like oscillating stars have been observed by the CoRoT (2007), Kepler (2009) and TESS (2017) space telescopes. By examining solar-like oscillating stars, new information has been obtained about stellar structure and evolution. Examination of cluster member stars that solar-like oscillation by applying asteroseismic methods is very important for studies on stellar internal structure and evolution. Thus, solar-like oscillating stars, which are cluster members formed at the same time from the same gas-dust cloud, can be modeled with internal structure models using asteroseismic methods. In this study, eight stars belonging to the NGC 6811 cluster, which are located in Kepler’s region and have evolved stars that solar-like oscillation, have examined. These eight evolved stars are modeled for the first time with the MESA evolution code. In addition, it has been determined that these stars are red-clumps by asteroseismic methods. Therefore, the internal structure models of stars are constructed with mass loss. The mass and radius range of the stars were determined from the model models as 2.23-2.40 M⊙and 8.47-12.38 M⊙, respectively. In this study, age-sensitive small speration for solar-like oscillating main sequence stars were calculated for these stars from the model oscillation frequencies. The model ages of the stars were compared with the calculated small separations. It has been determined that there are similar relations with the main sequence stars between the model ages and small separations of the red clump stars.